EP0817415A2 - Optischer Verstärker von Wellenlängenmultiplex - Google Patents

Optischer Verstärker von Wellenlängenmultiplex Download PDF

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Publication number
EP0817415A2
EP0817415A2 EP97111175A EP97111175A EP0817415A2 EP 0817415 A2 EP0817415 A2 EP 0817415A2 EP 97111175 A EP97111175 A EP 97111175A EP 97111175 A EP97111175 A EP 97111175A EP 0817415 A2 EP0817415 A2 EP 0817415A2
Authority
EP
European Patent Office
Prior art keywords
optical
division
wavelength
signal
optical signals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97111175A
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English (en)
French (fr)
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EP0817415A3 (de
Inventor
Tsutomu Tajima
Tadayuki Chikuma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Publication of EP0817415A2 publication Critical patent/EP0817415A2/de
Publication of EP0817415A3 publication Critical patent/EP0817415A3/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/29—Repeaters
    • H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
    • H04B10/293—Signal power control
    • H04B10/294—Signal power control in a multiwavelength system, e.g. gain equalisation
    • H04B10/296—Transient power control, e.g. due to channel add/drop or rapid fluctuations in the input power
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0221—Power control, e.g. to keep the total optical power constant

Definitions

  • the present invention relates to a wavelength-division-multiplexing optical amplifier device for amplifying a plurality of optical signals having different wavelengths, and more particularly to the stabilization of an amplified optical output signal from such a wavelength-division-multiplexing amplifier device.
  • the present invention is also concerned with a wavelength-division-multiplexing optical transmission system which employs wavelength-division-multiplexing optical amplifier device in an optical transmitter and an optical repeater.
  • optical linear amplifier devices are controlled by an optical amplifier control process which branches an inputted optical signal of the optical linear amplifier, detects the reception level of the optical signal with a reception level monitor, and controls the amplification factor of the optical linear amplifier depending on the detected reception level.
  • an optical amplifier control process which branches an inputted optical signal of the optical linear amplifier, detects the reception level of the optical signal with a reception level monitor, and controls the amplification factor of the optical linear amplifier depending on the detected reception level.
  • Wavelength-division-multiplexing optical transmission systems to which conventional optical linear amplifiers are directly applied suffer various problems.
  • two or more optical signals having different wavelengths are wavelength-division-multiplexed in a single wavelength band, and amplified by an optical amplifier for transmission.
  • One of the problems is that when one or more optical signals are interrupted for some reason, such a signal interruption is erroneously detected as a reduction in the inputted level of the combined optical signal, and the system increases the amplification factor of the optical amplifier, resulting in an increase in the amplification factor for each of the optical signals.
  • This phenomenon happens because the conventional optical amplifier control process branches an inputted optical signal, detects the reception level of the optical signal with a reception level monitor, and controls the amplification factor of the optical amplifier depending on the detected reception level.
  • Another problem is that while the amplification factor for each of the optical signals may be set to a desired level at an upstream optical signal terminal of the wavelength-division-multiplexing optical transmission system, the amplification factor for each of the optical signals tends to vary depending on the number of optical signals at a downstream linear repeater. This is because there has been no means whatsoever for transmitting information representative of the number of optical signals from the upstream optical signal terminals to the downstream linear repeater.
  • Another object of the present invention is to provide an optical in-line amplifier (optical repeater amplifier device) for use as each of linear repeaters connected in multiple stages, which is capable of keeping at a constant level the output power of each of the normal optical signals received from optical booster amplifiers irregardless of the number of optical signals even when one or more of the optical signals are interrupted for some reason, and of transmitting information representative of the number of optical signals to a downstream linear repeater or regenerative repeater.
  • optical in-line amplifier optical repeater amplifier device
  • Still another object of the present invention is to provide an optical amplifier device for use as a regenerative repeater, which is capable of keeping at a constant level the amplification factor for each of normal optical signals received from optical booster amplifiers or optical in-line amplifiers irregardless of the number of optical signals even when one or more of the optical signals are interrupted for some reason, for thereby achieving a desired amplification factor.
  • Yet still another object of the present invention is to provide a wavelength-division-multiplexing optical transmission system which incorporates such optical amplifier devices.
  • a wavelength-division-multiplexing optical amplifier device comprising a plurality of optical transmitting means for transmitting a plurality of optical signals having different wavelengths, respectively, optical combining means for wavelength-division-multiplexing the optical signals into a wavelength-division-multiplexed optical signal, optical amplifying means for amplifying the wavelength-division-multiplexed optical signal, optical branching means connected respectively to the optical transmitting means, for branching the optical signals into branched optical signals, optical signal count detecting means for receiving the branched optical signals and detecting the number of actually transmitted optical signals thereby to generate a control signal, and control means responsive to the control signal, for controlling the optical amplifying means to equalize a level of the amplified wavelength-division-multiplexed optical signal to a level depending on the detected number of actually transmitted optical signals.
  • the optical amplifying means comprises an amplifying optical fiber, a light source for transmitting a pumping light to the amplifying optical fiber, and an optical combiner for combining the pumping light and the wavelength-division-multiplexed optical signal with each other, and the control means includes pumping light control means for controlling an output level of the pumping light based on the control signal.
  • the amplifying optical fiber comprises an erbium-added optical fiber.
  • the optical amplifying means further comprises signal count superposing means for superposing information representative of the detected number of actually transmitted optical signals onto the amplified wavelength-division-multiplexed optical signal.
  • the signal count superposing means comprises a sine-wave signal generator for generating a sine-wave signal representative of the detected number of actually transmitted optical signals, and means for controlling the pumping light source to output the pumping light in a sine-wave form based on the sine-wave signal.
  • the wavelength-division-multiplexing optical amplifier device is used, for example, as an optical transmission device having an optical booster function in a transmission terminal station of a wavelength-division-multiplexing optical transmission system.
  • a wavelength-division-multiplexing optical amplifier device comprising signal count detecting means for detecting information representative of the number of optical signals from a wavelength-division-multiplexed optical signal composed of a plurality of optical signals having different wavelengths, respectively, optical amplifying means for amplifying the wavelength-division-multiplexed optical signal, control means for controlling the optical amplifying means to equalize a level of the amplified wavelength-division-multiplexed optical signal to a level depending on the detected number of optical signals, and signal count superposing means for superposing the information representative of the number of optical signals onto the amplified wavelength-division-multiplexed optical signal.
  • the wavelength-division-multiplexing optical amplifier device described above may be used as a linear optical repeater having an optical amplification function.
  • the wavelength-division-multiplexing optical transmission system includes the wavelength-division-multiplexing optical amplifier device as an optical transmission device and an optical repeater connected through an optical transmission path to the optical transmission device.
  • the output levels of optical signals from optical signal transmission terminal stations are branched respectively and detected by photodiodes, and the optical signals are counted by an optical signal count detector for setting an output level of an optical amplifier to a desired level.
  • an optical signal count detector for setting an output level of an optical amplifier to a desired level.
  • a sine-wave signal having a frequency depending on the number of optical signals is superposed on a direct current for energizing a pumping laser diode of the optical amplifier, thereby adding an auxiliary signal to the envelope of a main optical signal for transmission. Therefore, the information representing the number of optical signals is transmitted to a downstream linear repeater or regenerative repeater.
  • the number of optical signals may be detected by establishing reception level ranges and determining which of the reception level ranges the sum of the levels of actually received optical signals falls in.
  • all optical signals having respective wavelengths may be detected by a single photodetector through a variable-wavelength filter placed in a stage preceding the photodetector for detecting the level of each of the optical signals.
  • the received optical signal is branched by an optical coupler, and the information representing the number of optical signals, which has been superposed on the envelope of the optical signal, is detected by an optical signal count detector from the branched optical signal.
  • a DC voltage depending on the number of optical signals detected is applied as a reference voltage to a negative feedback circuit which controls the output power of the optical signal to achieve an optical signal output level depending on the number of optical signals detected.
  • a wavelength-division-multiplexing optical amplifier device according to a first embodiment of the present invention will be described below with reference to Fig. 1.
  • optical signal transmission terminal stations comprise a plurality of optical signal transmission panels 1, 2.
  • optical signals from two optical signal transmission panels 1, 2 are wavelength-division-multiplexed by way of example.
  • the optical signals from the optical signal transmission panels 1, 2 are branched into main optical signals and control optical signals by respective optical couplers 3, 4.
  • the control optical signals are converted to respective electric signals by respective photodiodes 6, 7 of an optical signal count detector 5.
  • the electric signals from the optical signal count detector 5 are then applied as a reference voltage to a negative feedback circuit 9 of an optical booster amplifier 8 to control a direct current therein for producing an optimum optical signal output level depending on the number of optical signals.
  • the optical booster amplifier 8 has a sine-wave generator 10 which is energized at different frequencies. Depending on the number of optical signals for adding a sine-wave signal to a current that energizes a pumping laser diode (LD) 11. In this manner, an auxiliary signal is added to the envelope of the main optical signals 12 from the optical couplers 3. 4 to transmit the information representative of the number of optical signals together with the main optical signals.
  • LD pumping laser diode
  • the optical booster amplifier 8 may comprise an erbium-added optical fiber amplifier, for example.
  • Fig. 2 shows a wavelength-division-multiplexing optical amplifier device according to a second embodiment of the present invention.
  • the wavelength-division-multiplexing optical amplifier comprises an optical in-line amplifier in a linear repeater, for example.
  • an optical signal supplied to a linear repeater 21 is branched by an optical coupler 22 in an input stage.
  • the branched optical signal is converted to an electric signal by a photodiode 24 of an optical signal count detector 23.
  • the electric signal is then applied as a reference voltage to a negative feedback circuit 26 of an optical in-line amplifier 25 to control a direct current therein for producing an optimum optical signal output level depending on the number of optical signals.
  • the optical in-line amplifier 25 has a sine-wave generator 27 which is energized at different frequencies depending on the number of optical signals for adding a sine-wave signal to a current that energizes a pumping laser diode (LD) 28. In this manner, an auxiliary signal is added to the envelope of the main optical signal 29 from the optical coupler 22 to transmit the information representative of the number of optical signals together with the main optical signal.
  • LD pumping laser diode
  • the optical amplifier device according to the first embodiment is used as an optical amplifier device in an optical transmission station, and the optical amplifier device according to the second embodiment is used as an optical in-line amplifier, thereby constructing an optical transmission system capable of stably transmitting wavelength-division-multiplexed optical signals.
  • the optical amplifier Before a wavelength-division-multiplexed optical signal is amplified, the number of optical signals is detected, and the optical amplifier is controlled depending on the number of the optical signals detected. Therefore, the optical amplifier can produce an optical signal output level depending on the number of the optical signals detected. Since information representing the detected number of optical signals detected is added to the amplified wavelength-division-multiplexed optical signal for transmission.
  • the transmitted wavelength-division-multiplexed optical signal can thus be amplified depending on the number of optical signals in an optical repeater downstream of the optical amplifier.
  • the optical amplifier device which is capable of amplifying the wavelength-division-multiplexed optical signal depending on the number of optical signals detected, may be incorporated in an optical transmission system comprising an optical transmission device and an optical repeater amplifier device for stable wavelength-division-multiplexed optical signal transmission.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)
  • Lasers (AREA)
EP97111175A 1996-07-04 1997-07-03 Optischer Verstärker von Wellenlängenmultiplex Withdrawn EP0817415A3 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP8174600A JP2904131B2 (ja) 1996-07-04 1996-07-04 波長多重光増幅装置と波長多重光伝送装置
JP174600/96 1996-07-04
JP17460096 1996-07-04

Publications (2)

Publication Number Publication Date
EP0817415A2 true EP0817415A2 (de) 1998-01-07
EP0817415A3 EP0817415A3 (de) 2000-03-29

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP97111175A Withdrawn EP0817415A3 (de) 1996-07-04 1997-07-03 Optischer Verstärker von Wellenlängenmultiplex

Country Status (3)

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US (1) US5995276A (de)
EP (1) EP0817415A3 (de)
JP (1) JP2904131B2 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2324667A (en) * 1997-04-25 1998-10-28 Nec Corp Wavelength multiplexed optical signal amplification control system
EP0812078A3 (de) * 1996-05-31 1999-03-03 Fujitsu Limited Optisches Übertragungssystem und optischer Verstärker
US6639716B1 (en) * 1999-02-08 2003-10-28 Fujitsu Limited Wavelength division multiplexing optical communication system and optical amplifying device

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3068500B2 (ja) 1997-04-25 2000-07-24 日本電気株式会社 光信号増幅伝送方式
SE9703000D0 (sv) * 1997-10-21 1997-08-20 Ericsson Telefon Ab L M Optical amplifier control
JP3102397B2 (ja) * 1997-12-10 2000-10-23 日本電気株式会社 光波長多重伝送システム
JP3166695B2 (ja) 1998-01-05 2001-05-14 日本電気株式会社 波長分割多重送信装置
DE19838788A1 (de) * 1998-08-26 2000-03-09 Siemens Ag Geregelter optischer Verstärker
JP2000269578A (ja) * 1999-03-18 2000-09-29 Fujitsu Ltd 光増幅のための方法、装置及びシステム
US20040017603A1 (en) * 2002-07-29 2004-01-29 Paul Jay Optical amplifier controller
JP2006060764A (ja) * 2004-07-20 2006-03-02 Mitsubishi Electric Corp 光通信装置及び光通信システム
EP2842243B1 (de) * 2012-03-06 2017-06-07 Adtran, Inc. Systeme und verfahren zur reduzierung von thermischen rückständen bei messungen mit optischem zeitbereichsreflektometer (otdr)

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5268786A (en) * 1991-03-15 1993-12-07 Mitsubishi Denki Kabushiki Kaisha Optical fiber amplifier and its amplification method
US5455704A (en) * 1991-11-08 1995-10-03 Mitsubishi Denki Kabushiki Kaisha Optical-fiber light amplifier
US5600473A (en) * 1993-06-04 1997-02-04 Ciena Corporation Optical amplifier systems with add/drop multiplexing
GB2280561B (en) * 1993-07-31 1997-03-26 Northern Telecom Ltd Optical transmission system
JPH0795161A (ja) * 1993-09-20 1995-04-07 Fujitsu Ltd 光増幅中継伝送システム
FR2715017B1 (fr) * 1994-01-13 1996-02-16 Alcatel Nv Procédé de transmission et liaison optique à multiplexage spectral avec amplification.
US5392154A (en) * 1994-03-30 1995-02-21 Bell Communications Research, Inc. Self-regulating multiwavelength optical amplifier module for scalable lightwave communications systems
JP3379052B2 (ja) * 1994-09-26 2003-02-17 富士通株式会社 波長多重光増幅装置及び光波長多重伝送システム及び光波長多重伝送方法
JP2809132B2 (ja) * 1995-06-07 1998-10-08 日本電気株式会社 光増幅監視装置
JPH09214428A (ja) * 1996-02-02 1997-08-15 Nippon Telegr & Teleph Corp <Ntt> 波長監視方法およびそれを用いた光増幅装置
JPH09321701A (ja) * 1996-05-31 1997-12-12 Fujitsu Ltd 光通信システム及び光増幅器

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6259553B1 (en) 1996-05-13 2001-07-10 Fujitsu Limited Optical communication system and optical amplifier
EP0812078A3 (de) * 1996-05-31 1999-03-03 Fujitsu Limited Optisches Übertragungssystem und optischer Verstärker
US6023366A (en) * 1996-05-31 2000-02-08 Fujitsu Limited Optical communication system and optical amplifier
US6108123A (en) * 1996-05-31 2000-08-22 Fujitsu Limited Optical communication system and optical amplifier
US6282017B1 (en) 1996-05-31 2001-08-28 Fujitsu Limited Optical communication system and optical amplifier
US6452719B2 (en) 1996-05-31 2002-09-17 Fujitsu Limited Optical communication system and optical amplifier
GB2324667A (en) * 1997-04-25 1998-10-28 Nec Corp Wavelength multiplexed optical signal amplification control system
GB2324667B (en) * 1997-04-25 1999-06-16 Nec Corp Optical signal amplification control system
US6639716B1 (en) * 1999-02-08 2003-10-28 Fujitsu Limited Wavelength division multiplexing optical communication system and optical amplifying device

Also Published As

Publication number Publication date
EP0817415A3 (de) 2000-03-29
JP2904131B2 (ja) 1999-06-14
US5995276A (en) 1999-11-30
JPH1022980A (ja) 1998-01-23

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